CNN.com does not accept pop-up advertising on its home page, nor on the main and story pages in World, U.S., Politics, Law, Education, Special Reports and CNN TV show sections.

Pop-up ads are only permitted on CNN.com's Entertainment, Health, Science and Space, Technology, Travel and Weather sections. Pop-under ads are permitted on all section fronts and the home page.

Pop-up ads are displayed in a separate window on top of content already visible in your browser. A pop-under ad appears in a new browser window behind an open window.

How many should I see? And how often?

You should only experience pop-up or pop-under ads approximately once every 12-hour session. A user session expires when you close your browser window OR after 24 hours.

What if I am seeing much more than that?

There are several factors that could contribute to seeing additional pop-up advertising. It's possible that a site you visited prior to CNN.com is spawning delayed advertisements or "exit ads." Another possibility could be that spyware or adware programs have been installed on your computer -- without your knowledge.

What is spyware/adware? How do I know if I have it? How can I get rid of it?

Spyware is software that covertly tracks a consumer's behavior and online activities. The spyware uses the data it collects to target and deliver pop-up advertisements and other promotional messages to that consumer. Adware is a specific form of spyware. When adware is downloaded (again, most often without the consumer's knowledge) the ads it displays are already embedded in the application.

There are free and commercial programs available to detect and remove spyware and adware applications. Performing a Web search for "spyware removal" or "adware removal" will point you to products such as AdWare and SpySweeper. See quick web search results on spyware for more.

Also, Norton and McAfee have spyware upgrades to their antivirus software. It is your responsibility as the consumer to keep these spyware programs upgraded on your computer.